Intraoperative radiotherapy (IOR) of 15 patients with advanced pancreas cancer using 9-15 MeV electron beams of a linear accelerator showed, that IOR is a practical and safe procedure with demonstrable major tumoricidal effect in all five patients who came to autopsy. Although 13 of the 15 patients have died, none of the five autopsied patients succumbed to a local recurrence in the treated area. To avoid complications with IOR the radiation doses should be kept below 3000 rad for small volumes and below 2000 rad for large volumes. If these limits are respected and the intestines except the involved duodenum are kept out of the radiation beam, the risk and inconvenience of adding IOR to the usual abdominal exploration with biopsy and bypass is negligible. If, however, abdominal exploration and bypass has already been performed, a second operation for the purpose of IOR is advised only if the primary is small and no metastases are demonstrated.